This invention relates to the telecommunication arts and more specifically to an apparatus and method for sealing a reenterable splice enclosure and related service connections in a reenterable protective housing to protect both splices and service connections against detrimental environmental effects.
Dependency upon telecommunications and data communications presses the technology to provide consistent high quality communications with minimal down time. A key to providing high quality communications with minimal down time is the protection of installations at critical points and provision for quick and efficient in-field repairs.
In the delivery of telecommunication services it is common to install multi-carrier primary cables to provide communication service to a predetermined area. The primary cable consists of a number of individual binder groups consisting of multiple line pairs. At specific points along the primary cable, connections must be made to route individual wire pairs to end user locations. Primary cables are typically very long continuous cables and are not conveniently manufacturable with specific lengths between predetermined break off points. Specific binder groups are extracted from the primary cables and their line pairs are spliced to a secondary cable. The secondary cable is joined to a service cable at a terminal block. The service cable is then routed to an end user location.
The splice connection between the secondary cable and the primary cable wire pairs and the terminal block connections must be protected from the environment since moisture, oxygen, chemicals (both natural environmental and man-made pollutants) and the accumulation of dust and dirt may individually or cumulatively act to damage the splice and terminal block connections. Typically, prior art telecommunications housings protect a portion of primary cable and connections in what is referred to as a "pedestal". A pedestal has an elongated sleeve-like cover structure having a closed end and an open end which is positioned over the splice connections and terminal block. To protect the splice connections and the terminal block from detrimental environmental effects, the open end of the pedestal cover must be sealed relative to the pedestal and relative to entering and exiting cables.
Current pedestal sealing technology can be yet further improved to improve telecommunications quality, to minimize down time for or field service repairs to improve accessibility for field servicing and to improve the reliability of the installation following field service or repairs. For example, in one typical prior art arrangement, the seal which seals the pedestal cover to its base is the only reenterable seal for both the splice connections and the service connections. The problem with this sealing arrangement is that access to splice connections is not required every time a worker works on the service connections. The splice connections may be sealed with tape, sealants and the like and hence are difficult to access. When only the service connections need to be accessed but not the splice connections, the splice connections are nonetheless exposed unnecessarily, thereby potentially decreasing their integrity. Since the splice and service connections are extremely important to the integrity of the system it is desirable to avoid unnecessary exposure of either.
Another example of a prior art pedestal arrangement is shown in U.S. Pat. No. 4,902,855 to Smith. In this prior art arrangement, the cables are inserted into a pedestal and the open end is sealed. Sealing is accomplished through a labor intensive tape wrapping process. This method forms a seal which is inherently non-uniform thereby creating potential for problems with the fit inside of the pedestal and/or any circumferential compression fitting or clamp used to engage and seal the structure. Further, depending upon the type of tape used, ground wires may have to be separately wrapped prior to incorporation into the common seal. The sealing arrangement formed is then inserted into the open end of the pedestal and a shrink tubing is positioned and shrunk around the outside of the dome to retain the sealing member therein. Alternatively, a clamp may be used, as shown in the above-mentioned patent to Smith.
As mentioned above, this type of prior art sealing system is inherently extremely time consuming and material intensive. Further, this system risks cutting or otherwise damaging cable jackets in attempting to remove the shrink tubing as well as the sealing member when repairing or modifying splice connections. Additionally, sufficient supplies such as tapes and shrink tubing must always be on hand to avoid further delays when installing or repairing splice connections.
Other prior art arrangements make use of grommet like members, which must be carefully cut to size and fitted with the cables and which require additional lubricants for installation. These grommets must be press fitted within a bulkhead opening and circumferencially or radially compressed about a cable or cables for sealing. This arrangement may also require additional taping of cables and the application of additional viscous sealants. This arrangement does not permit easy re-entry once the enclosure is sealed. Nor can the sealing materials, grommets, etc. be reused after reentry, rather, the entire above-described process must be repeated employing a new grommet or grommets and other materials.
Several problems arise with the prior art in the installation of the pedestal. Primary cables are typically laid in the ground by a cable-laying contractor. This contractor also brings out a loop of cable at each location where a pedestal is to be installed. After the cables have been laid, the telecommunications company provides a skilled installer to form the appropriate cable splices and connections required at each pedestal location. Each pedestal location may be very complex and require a substantial number of cable splices and connections. It can be seen that the division of labor regarding the installation of the cable and the connection of the cable is quite well-defined.
However, some prior art pedestal designs require completion of all of the splice connections upon initial installation of the pedestal base and protective dome. It would be preferable to provide an apparatus which would permit initial installation of the pedestal base and dome by the cable-layer, leaving the removal of the cable sheath and splicing for the qualified technician.
This problem with some prior art designs occurs because of the nature of the primary cables. Primary cables may include hundreds of small individual wires which are quite flexible but which are surrounded by a relatively rigid protective sheath. When a pedestal is installed, typically there is a base, a bulkhead, and a dome portion. In the above-mentioned prior art design, the bulkhead and base member are an integral piece. The sheath-covered cable is typically much too rigid to insert the loop brought up by the contractor through an aperture formed through the bulkhead to receive the cable. Thus, the prior art design requires the stripping of the sheath from the cable by the skilled technician in order to install the pedestal, since allowing the relatively unskilled cable-installer perform the sheath-stripping operation could cause damage thereto.
The complications discussed above are further increased due to the nature of the underground communications cable network. The pedestals are typically the most conveniently available access node to the cable network, and therefore are extremely important in the integrity and operation of the network as a whole. If the pedestal is installed by the cable-laying contractor, the primary cable may be damaged due to the lack of training and skill in such technically precise operations. If the connection technication is left to install the pedestal the loop of primary cable protruding from the ground is left unprotected until the pedestal is installed. Further, the connection technician's time is not economically spent in the manual, relatively unskilled job of installing the base of the pedestal thereby increasing telecommunications costs due to labor inefficiencies.